Low carbon pitch compositions



s. P. MILLER Feb. 9, 1932.

LOW CARBON PITCH COMPOSITIONS Filed Dec. 29, v192'? s sheets-sheet 1mmf.

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LOW CARBON FITCH COMPOSITIONS,

Filed Dec. 29, 1927 3-.Sheets-Sheet 3 lnaz'ny I ppara tus .Storage F45INVENTOR i BY r M, /CQM 777m i( mb ATTORNEYS Patented Feb. 9, 1932unirse .s'rAres STUART PRMELEE MILLER, OF

BARRETT COMPANY, F NEW YORK, N. Y.,

PATENT OFFICE ENGLEWOOD, NEW JERSEY, ASSIGNDR T0 THE A GORPRAIIGN F NEWJERSEY LOW CARBON PITCH COMPOSITIONS Application filed December 2e,1927. Serial No. 243,306.

5 oven and other coal distillation plants and from coke oven and gasretort tars. h

ln the ordinary oper-ation of by-product coke oven and gas retortplants, the gases from the ovens or retorts are cooled to separatetar'therefrom and the tar is shipped to tar distillation vplants andthere distilled to produce distillate oils and pitch residues.

The pitches produced by the distillation' of coke oven tar, for example,have a content of free carbon too high. to permit them to be employedfor certain purposes where a low content of free carbon 'is required,and, for the production of low carbon pitches, it is customary to employtars from other 2o sources, particularly water-gas tar, either alone or,blended with coke oven tar before the mixtureis subjected tovdistillation.

The present invention provides for the production of nev.7composite'pitch compositions of low carbon content directly at colteoven and other coal distillation plants and from coke oven or gas retorttar.

In referring to content of carbon orvfree carbon in tar and pitch I usethese terms in their ordinary significance to meanthe ingredientsremaining insoluble on digestion of the tar or pitch with benzol orother similar solvent, and to include not only elemental or molecularcarbon but also insoluble inorganic impurities and insolublehydrocarbons ofhigh molecular Weight.

According to .the present invention, a lo'w carbon tar is'separated fromthe colte oven or other coal distillation gasesl given oli from theindividual coke ovens or gas retorts during the early period of thecoking or gas' making operationand this louT carbon tar is subjected todistillation to form a relatively` high melting point but low carbonpitch, and this pitch is blended with additional tar to form a composfteblended pitch product o' regulated low carbon content.

ln my companion application, Serial No. 243,305, filed December 29,1929, l havedescribed the production oi low carb-on pitches byseparately collecting low carbon tar from the gases given oil during theearly portion of the coking or gas-making operational; coke oven or gasretort plants and distilling such low carbon tar toproduce low carbonpitches of varying melting point and of low carbon content.,

The present invention isv distinguished from the invention of saidcompanion ap lication by the production of low car on pitches or' highermelting point than desired inthe final product, and the blending of suchhigh melting-point low carbon pitches with additional tar or softerpitch to torni a coinposite blended product.

The production of the low carbon tar and pitch and the distillation ofthe low carbon tar to make the pitch can advantageously be carried outin accordance with the process of my said companion application, but thedistillation i's carried to a point such that .the pitch produced is ofa much higher melting point than desired in the nal product.

While the low carbon pitch can be distilled in various kinds of tarstills, including the ordinary externally heated tar stills, it can moreadvantf-.geously be distilled by bringing it into direct and intimatecontact with hot coke oven or other coal distillation or gasilicationgases, since such c istilla tion can readily be carried out at the colteoven or gas retort plant or at the water gas plant and is accompaniedwith. much less decomposition of oil constituents and less in crease incar-bon content than when the distillation is carried out in externallyheated tar stills. The distillation of the tar at the coke oven or gasretort plant by means of het coal distillation gases is alsoadvantageous in that it permits the tar to be continuously distilled andpitch of regulated melting point produced and the hot pitch to beutilized directly for blending with the tar or softer pitch, which taror softer pitch may also be produced and employed in a heated condition.

The extent to which the distillation is ear ried can be varied, andwilldepend upon the nature of' the composite products to be produced.Ptches of intermediate melting point can be produced of melting pointsfor -eX- ample, around 165 to 225 F determined by the cube-in-airmelting point method, but pitches can advantageously be produced ofovver melting point and likewise of much higher melting point, around250 or 300 F. or even around 4000 F. or higher, since the low carbontars lend themselves to distillation, in contact' with hot coaldistillation gases, to produce pitches of soph high melting point. Theproduction of high melting point pitches has the advantage that it givesa high yield of heavy oils which are recovered as valuable products ofthe process.

In my companion application, Serial. No. 243,307, filed December 29,1929, I have described the production of high carbon tar from the gasesgiven olf near the end of the coking or gas-making operation and thedistillation of such tar for the production therefrom of high carbonpitches; and in my comanion application Serial No. 243,308, filedI)ec`ember 29, 1929, I have described the diS- tillation of the highcarbon tars to produce high carbon pitches of higher melting points thanthat desired in the final roducts, and the blending of such high meltingpoint high carbon pitches with tar for the production of composite pitchproducts of regulated high carbon content. The improved products of thepresent invention can be produced at the same time as the processesdescribed in my said companion applications, although .the presentinvention is of broader application and the low carbon pitches can beproduced in cases where a high carbon pitch is not simultaneouslyproduced.

In the practice of the invention at coke oven plants, for example, theplant may advantageously be provided with tivo collector mains, bothunited to the same coke ovens, and with valves for connectinJ each ovenwith one of the other mains so that the gases can be collected from thevarious ovens in one main during the vdesiredinitial eriod of operationin order to collet therein the gases from which lov:r carbon tar iscondensed, leaving the ases from the later period of operation toIiecollected in the other collector mains to give tar of higherY carboncontent. The tars from the respective collector mains as Well as fromthe separate condensing systems, are kept separate and the low carbontar is subjected to distillation by itself, using either the heavy tarfrom the collector main or the lighter' tar from the condensers orcombining the heavy and the lighter tars to forni a composite low carbontar which is then subjected to distillation.

The higher carbon tar simultaneously separated from the other collectormain may be employed as tar or may' itself be subjected to distillationfor the production of high carbon pitches therefrom. rIhe o )eration ofthe collector mains and of the con ensers may be conducted in accordancewith the usual practice by circulating ammonia liquor, or ammonia liquorand tar, through the collector mains, and by cooling the condenserseither directly or indirectly to separate the lighter tars or tarry oilsfrom the gases; but in regulating the operation of such systems,thegases will be collected in one or the other of the collector mains,depending upon the carbon content desired in the tar, and only suchportion of the as from the early period of operation will be collectedtogether as will give a tar of sufficiently low carbon content so thatupon distillation it will give a low carbon pitch suitable for use forblending With additional tar or soft pitch in the practice of theinvention. The gas may be collected, for example, only during theinitial third or quarter of the coking operation, although in some casesit may be collected during the first half or more of the cokingoperation, depending uponv the carbon content required in the low carbonpitch composition.

The distillation of the 10W carbon tar is advantageously carried out inshort collector mains or stills i to which the gases from a plurality ofove s are directly led at a high temperature and into which the tar isintroduced and brought into intimate contact with the gases. The tar maybe sprayed into the gases, or the operation can be promoted by providingmechanical agita-ting devices such as rotating discs, or rotating rollsor rotating paddles operating at a suiiiciently high speed toeffectively atomize or spray the tar and pitch into the gases to securerapid and effective distillation, and to Wash down the surfaces of themain. This distillation can be carried out continuously, to producecontinuously high melting point low carbon pitch, which is drawn off ata high temperature and advantageously blended While still hot with thetar to produce the composite com osition.

T e tar orV softer pitch which is blended with the high meltingpointp'itch may itself be a low carbon tar or pitch such as that fromwhich the pitch was produced, and in this Way a pitch of minimum carboncontent can be produced. Where such a minimum carbon content is notrequired, a tar of higher carbon content can be employed, such asordinary coal tar comprising the total tar from the coke oven operation,or even in some cases high carbon tar to a greater or lem extent.So'also, I do not exclude the blending with the new high melting pointlow carbon pitches of other tars than coke oven tars, since in somecases low carbon tars such as, for example, water-gas tar, or verticalretort tar, or low carbon pitches from Water-gas or vertical retorttars, may be included in the composition. The blended pitch compositionwill vary in properties and characteristics depending upon the nature ofthe tar employed,

CII

as Well as the proportions of the tar and pitch, and the melting pointand carbon content and other properties of the pitch itself.

The blending of the high melting point pitch with the tar isadvantageously accomplished by introducing continuous streams of the hotthinly fluid pitch and of the tar to be blended therewith into a mixingchamber. The tar itself may be hot or may be preheated to dehydrate itor to remove lighter oils therefrom. The heavy tar froml the collectormains may be employed While still hot, or other tar may be separatelypreheated or distilled to a greater or less extentA to give a heaviertar, or soft itch, partly freed from lighter oils, for the. lendingoperation. By introducing continuously streams of the pitch and tar intea suitable receptacle, such as a nearlyempty tank, the streams willblend with each other and produce a uniform blended product. Such ablending operation is desirable if the tar which is introduced containsWater, since the temperature of the pitch will ordinarily be so high asto cause rapid vaporization of the water and foaming of the mixture, andthe use of such a large receptacle permits the Water vapor and otherlight oils to be removed conveniently, and avoids any objection fromfoaming. The heat of the hot' thinly tluid pitch results in giving aheated mixture, and promotes the mixing operation, as well as thedehydration and in some cases the partial distillation of the tar. Theblending may of course be done batchwise. i

The vaporized Water and oil constituents, vaporized during the mixing ofthe pitch and tar, can be Withdrawn continuously from the mixingreceptacle, and the oil and Water then condensed, and the oil separatedfrom the wa- P ter by providing a suitable condenser. The blendedproducts can be Withdrawn continu-- ously from the mixing receptacle anddelivered to suitable storage containers. The heat of the hot pitch willunder most circumstances be sufficient to give va resulting het mixturesuiiiciently fluid to permit it to be drawn otl and handled. as a liquidproduct, Without difficulty in handling, although the composite productafter cooling may he of a solid character.v The tar orsoft pitch may beheated, if necessary. before blending to secure fluidity of the finalfluid.

The proportions in which the high melting point lou7 carbon pitch andthe tar are ad* mixed can of course be varied, depending upon themelting point of the pitch and 'the melting point and other propertiesof the blended product. For low carbon pitches having a melting point oiaround 'i60-17 0 F. (by thecube-in-air melting point method) such as aredesired tor saturating libre conduits for telephone cables, thedistillation of the. low carbon tar can be carried to a point.considerably above that of the pitchdesired,

for example, to 225 or even to 300 F.

or higher melting point, and the resulting pitch then blended With tar,either raw tar or tar which has been subjected to preliminary i tent otthe heavier pitch constituents, suchas those remaining after thedistillation of the tar to produce `the high melting vpoint pitch. Suchcompositions contain relatively vless of the intermediate products whichare removed from the pitch during its production; and such compositepitches commonly contain somewhat more of the lighter oils present inthe'tar andwhich are removed during the distillation to produce a lowcarbon pitch of similar melting point to that of the blended product.

The present process is likewise difierent-iated from the process of mycompanion application, Serial No. 243,309, tiled December 29, 1929, bythe carrying out of the dis- .tillation to produce a lon7 carbon pitchof higher melting point that that desired, with simultaneous productionof a high yield of heavy distillate oils, and the blending of the highmelting point pitch with additional tar, which has not been subjected todistillation` or -which has been distilled only to a limited extent. Thepresent process enables a much smaller amount of tar to be distilled,but

distilled to a much higher melting point itch and with increased yieldof high boiling point oils, and it enables a considerable amount of tarto be employed without subjecting it' to distillation for the productionof pitch therefrom.

As an example ofthe practice ofthe invention, the gases from the firstthird, quarter or half of 'the coking period ofa coke oven plant can becooled in the separate collector main or mains by ammonia liquor, orammonia liquor and tar, to separate a heavy low carbon'tar from thecollector main, and the Cgases can then be further cooled inthe conensers to separate a lighter tar of low carbon content therefrom. Theheavy tar alone or the lighter tar alone or both tars ladmixed together,can then be subjected to distillation in a separate short collector mainor distillation tank, into which the hot coke oven gases from several ofthe ovens are directly introduced, and in which the tar is brought intointimate contact with lthe lhot gases. The distillation can be carriedup to the point of producing, for example, a pitch of 165 to 225 F.melting point or even up to a point of producing a pitch ot 300 F.melting point or 400 melting point or even higher in some cases. Theproduction of the higher melting point pitches is accompanied with somedecomposition and increase 1n carbon content, but with the low carboncontent of the tars employed, the pitches, even of high melting point,are still relatively lov.7 in carbon content. For the production of thehigher melting point pitches, it is advantageous to omit Ispray nozzlesin the distillation box or main and to employ a mechanical agitatingdevice, such as rotating discs or rotating rolls or paddles, rotating ata suf ficient speed to atomize the tar or pitch into the gases toeffectively scrub the gases and bring the tar and pitch into intimatecontact therewith.

The resulting high melting point pitch of low carbon content can then bedrawn off continuously and supplied continuously to a mixing tank intowhich a supply of tar is also continuously added. and in which theblend-- ing of the pitch and tar takes place to give a resulting hotmixture of a homogeneous character which then may be drawn off tostorage tanks or to other place of shipment or of use.

The invention can be applied in connection with the by-product recoverysystems of existing coke oven plants particularly those which havetwocollector mains and two vcondensing systems for the separateproduction of rich gas and of lean gas for fuel purposes. In suchsystems, as now operated, the tars from the respect-ive mains arecollected together as a composite product, and the separate collectionof the rich and lean gases depends upon the B. t. u. or illuminatingvalue of the gases after the tar has been separated from them. Thepresent invention provides for the separate collection of the'tar fromthe rich and lean gases. and the regulation of the rich. and lean gasmains is conducted from the standpoint of the tar produced, and not fromthe standpoint of the character of the gas after the tar has beenseparated. In such plants, a separate distillation main or still isprovided for bringing the tar into intimate contact with' the hot cokeoven gases at a sufficiently high temperature, and a mining device orchamber is provided for mixing the resulting high melting point pitchwith ladditional tar to 'form the composite product.

The provision of separate collector mains and separate condensingsystems such that the high and low carbon tars can be separatelycollected and kept separate. and so that the heavier and lighter tarscan he separately collected and kept separate, enables the low carbontars in part or in whole to be distilled for the production of the highmelting point low carbon pitches, and gives a variety of tars forblending with the resulting pitches, these tars including the heavy lowcarbon tar itself, the lighter lowk carbon tar. and the heavier andlighter high carbon tars, or a blend or mixture of these in any desiredproportions.

The present invention is of particular value for the production of lowcarbon pitch compostion at coke'oven plants from coke oven tar but inits broader aspects it is applicable similarly to other coaldistillation plants. Gas retort plants can be operated in asimilarmanner with. segregation of the gases given oil' during the earlyportion ofthe gas making operation in the individual retorts andseparation of a relatively low carbon tar from such gases,withdistillation of such low carbon tar to produce low carbon pitch andblending of such pitch with additional tain The low carbon pitches fromhorizontal or inclined gas retort plants will be higher in free carbonthan the low carbon pitches similarly produced at coke oven plants andwill more nearly resemble ordinary coke oven tar pitches. The low carbonpitches from intermittent vertical retorts will be unusually low incarbon content. -The various pitches can be blended in varyingproportions with different tars, or even with other pitches to giveblended products of regulated low carbon content. The oils produced bydistillation of the low carhon'pitches will vary with. the low carbontars distilled and themselves form valuable products of the process. Theprocess makes possible the production of increased yields of higherboiling oils from the tar utilized, while leaving increased amounts oflow boiling oils in the undistilled tar blended with the high meltingpoint pitch.

The invention will be further described with reference to theaccompanying drawings which show apparatus adapted for the production ofthe new pitch compositions.

ln the accompanying drawings Fig. l is a plan View of a portion of acoke oven battery;

Fig. 2 is a cross-sectional view of one of the collector mains;

Figs. 3 and 4 are enlarged sectional views of the short collector mainor still; and

Figs. 5 and 6 are details in section of the blending apparatus.

Referring to the drawings, 5 indicates a battery` of ovens which areconnected by uptake pipes and goose-necks to valve boxes y whichcommunicate with collector mains 8 and 9. Valves 10 are arranged in thevalve boxes to permit the direction of the hot coke oven gases into oneor the other of the collector mains depending upon the stage of the coaldistillation operation in the particular oven to which the valve box isconnected. Thus, by operating the valves rich and lean gases from theseveral ovens of the battery can be collected separately in the collector mains wherein they are cooled to the desired extent by ammonialiquor introduced through spray nozzles ll which are supplied through apump 12 and pipe 13 from a source of ammonia liquor such as a tank 15.

From the collector mains the gases carrying oil vapors and partiallycondensed tarry constituents are delivered throughv cross-over mains 16and 17 to condensers 18 and 19 in which the gases are further cooled toseparate the oil constituents. The tarry oil together with ammonialiquor canbe withdrawn through pipes 2O and 21 and delivered todecanters 22 and 23 wherein the ammonia liquor is separated from theoils and delivered to storage tanks for subsequent recovery of ammoniatherefrom. The oil can be deliveredv to suitable storage receptacles 22and 23 and the ammonia liquor can in part be returned if desired forfurther use as a cooling medium either inthe collector mains or in thecondensers. The excess will be worked up for recovery of ammoniatherefrom. The gases escaping from the condensers are delivered throughpipes 24 and 25 to exhausters 26 and 26 and thence to equipment (notshown) for the separation of ammonia, light oils, etc.

The tar and liquor which separated in the collector mains can bewithdrawn through pipes 27 and 28 to receptacles 29 and 30 in which taris separated and withdrawn to re'- ceptacles 29 and 30. The tar from therich gas main contains a relatively low proportion of free carbon andthis tar is subjected to distillation in a suitable still, such, forexample, as a short collector main or still 31 which is disposedpreferably at. the rear of the ovens and is connected to a plurality ofovens so that hot coal distillation gases pass continuously through theshort collector main or still. distilled is introduced into the main orstill 31 at one' end through pipe 32. The main or still is provided witha cylinder or roll 33 adapted to be rotated at a high rate of speed byelectric motor 34. The roll dips into the tar and pitch in the bottom ofthe main or still and the rapid rotation atomizes the tar and pitch, inthe form of lfinely disseminated spray, into the gases passing throughthe main or still. ln thus mingling with the hot gases the tar isdistilled to produce pitch and the volatile constituents are separatedand join the gases which pass up through setting tower 35, during whichpassage the tar spray and globules entrained in the gases settle out andare returned to the main or still 31. The gases may be withdrawncontinuously through a pipe 37 and delivered to a condenser 38 locatedat any convenient place wherein the oil constituents can be separatedfrom the gases. Thereafter the gases may be delivered through a pipe 39to the eXhauster and mingled with the remaining gases from the ovens ofthe batter v 'llhe pitch produced in the short collector main or stillcan through a pipe 40 and delivered to the blend- The tar to bev bewithdrawn continuously ing apnpar'atus 41. The tar or other material tobe lended with the pitch is similarly inn troduced through a pipe 42,the two pipes being directed so that the streams are mingled as theyenter the chamber. The tar and pitch thus blend toproduce a producthavingthe desired characteristicswhich can be withdrawn continuouslythrough a pipe 43 and delivered to suitable storage receptacles 46.

Owing to the relatively high temperature of the pitch the tar which isblended therewith will be heated and any moisture present therein,together with volatile oil constituents, will be vaporized immediatelyupon contact between the tar and pitch. The vapor can be withdrawn as itis released through a pipe 44 and delivered to a condenser 45 whereinitv is cooled. The oil thus recovered may be mixed with oil obtained bythe cooling of the other gases from the system or it may be returned tothe pitch in 41.

In a similar manner the new pitch compositions of the invention can beproduced at other coal distillation plants, particularly gas retortplants, where a similar segregation of the gases and'production of lowcarbon tar and pitch can be carried out with blending of the high-melting point low carbon pitch and additional undistilled or partlydistilled tar to form various blended pitch compositions of regulatedcarbon content and other properties. lt will be understood that variouschanges may be made in the details of the operation and in the apparatusand process and in the character of the composite products produced andthat the invention makes possible a wide range of products which can beregulated to a greater or less extent by regulating the carbon contentof the tar distilled, the extent to which the distillation is carried,the kind of tar blended with the pitch and the proportions of theblended ingredients, etc.

1. New blended pitch compositions, comprising low free carbon pitch ofhigh melting point blended with coal tar, such pitch resulting from thedistillation of low carbon` tar separated from the gases produced duringthe early period of operation of the ovens of a coke oven or gas retortplant.

2. New low carbon pitch compositions, comprising a. blend of low carboncoal tar and of high melting point pitch resulting from the distillationof such tar,`the low carbon tar beingv obtained from coke oven or othercoal distillation gases during the early period of the coking or gasmaking operation.

In testimony whereof l affix my signature.

STUART PARMELEE MILLER.

CERTIFICATE oF eoaRECTioN.

Patent No. 1 844,899. Granted February 9, 1932, to

STUART PARMELEE MILLER.

it is hereby eeitiied that emef appears in the primed specification ofthe above numbered patent requiring eoecion as follows: Page i, line 49,and page 2 lines i6 ami 23, 'for the year "1929" read 1927; page 3,lines 93 and 94, foi "Seria No. 243,399, ied December 29, 1929" readSexiai No. 243,305, filed December 29, 1927; and. mat the said LettersPatent should be read with these correetion therein that the samemayconform to the record ofthe case in the Patent Office.

Signed. and sealed this 17th day of May, A. D. 1932.

M. J. Moore, (Saai) Acting Commissioner of Patents.

